We already know that the upcoming Crisis on Earth-X crossover (described as a “four-hour movie” by Stephen Amell) will take ample inspiration from the Crisis on Infinite Earths storyline.
Specifically, it leads us to believe that there’s a possibility that Earth-38 could eventually become part of the Earth-1 Arrow-verse.
Of course, the fact that the commercial ends with the promise that Big Belly Burger is eventually making a move to National City (a.k.a the home of Supergirl) has our mental wheels turning.
If the crossover follows the source material, even loosely, then it is entirely possible that we could see a convergence that brings Kara Zor-El into the fold as an Earth-1 hero.